Cleaning of metals, etc.



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mama July 2, 1929 UNITED STATES Examiner 1,719,167 PATENT OFFICE.

GEORGE D. CHAMBERLAIN, OF ASHLAND, KENTUCKY, ASSIGNOR TO B. '1. VANDER- IBILT COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

CLEANING OF METALS, ETC.

R Drawing. Application filed January 11 This invention relates to the pickling and cleaning of metals, and particularly to the pickling of iron or steel, to remove scale therefrom, although the invention is of more or less general application to the cleaning or pickling of metals such as iron or steel for the removal of oxides or scale therefrom.

The pickling or cleaning of iron or steel is commonly effected by means of acid pickling or cleaning baths which dissolve the scale or oxide from the metal. The pickl ng baths commonly employed are acid baths which often attack the metal as well as the scale. This action on the metal is undesirable and objectionable, involving not only excessive consumption of acids, but also corrosion or dissolving of metal and tending to give a rough or pitted surface.

The present invention provides an improved bath for pickling or cleaning iron or steel and also an improved process of pickling or cleaning the metal in which the acid pickling bath has incorporated therein a small amount of a condensation product of a nitrogenous base with a ketone.

I have found that the addition of a small amount of a suitable condensation product of a nitrogenous base with a ketone prevents or retards or inhibits the attack of the acid pickling bath on the metal Withoutinterfering with the removal of scale or oxide by the acid bath.

The agents which are added to the cleaning or pickling bath, according to the present inaaleatinn; inelndavadeu .serdsrs t e xrre ib a scs vfith iketonesl' -Amnngthesemefbe -qafiiiij i.is9eqgis i nrcdn. t ..otr iqesl asq n b s c a mmonia.and.. rials.slliifi sllis i fiii hydroxyl amine. Certain condensation prod iict s' o f iiiti'figiious bases with acetone are particularly advantageous such as tl e conv densationproduct of acetgllsawltlh, amnio'ni'a.

A suitable method of making thecon'densation product of acetone with ammonia is to introduce ammonia gas into acetone containing powdered calcium chloride in suspension until the acetone is saturated, and then allowing the reaction mixture to stand until the reaction is completed. The resulting oily product can be freed from excess acetone and ammonia by distillation, and can be further treated to separate the different acetone amine products or fractions therefrom. Condensa- 1927. Serial No. 160,526.

tion products of other nitrogenous bases and ketones may be formed in a similar manner, using other nitrogenous bases and ketones as starting products.

The acid pickling baths with which the agents mentioned are used may be acid baths such as are commonly employed for pickling or cleaning iron and steel, containing for example, about 10% of sulfuric acid. Such baths are gradually impoverished by the action of the acid in removing the scale or rust and their content of ferrous sulfate increases until the bath becomes too weak or too concentrated in ferrous sulfate for further use. Instead of using sulfuric acid baths, other acid baths can be used, including acid sulfate baths.

The amount of the condensation product added to the bath for carrying out the pickling or cleaning operation can be varied. In general, only a small amount of the condensation product is required, for example,

a small fraction of one percent. In the case of the condensation product of acetone with ammonia, for example, about two pounds of the condensation product can be employed so for each ton of 60 degreeacid used in the pickling bath. The condensation product employed should be one which is stable and does not decompose to any objectionable extent in the acid bath. The carrying out of the pickling or cleanmg operation may be the same as in ordinary practice. For example, the pickling can be carried out continuously by passing the material to be pickled, such as wire or sheets, 0 through a number of baths in a regulated manner; or by immersing the article to be pickled "lhthe pickling bath for a suitable period of time. The temperature of the bath can be varied, ordinarily being around 150 or 180 F. The pickling bath may be replenished by the addition of further amounts of acid until the iron sulfate reaches too great a concentration. a

The addition of the condensation product to the bath prevents or retards or inhibits the action of the acid bath on the metal without interfering with the removal of scaleor oxide. The formation of hydrogen by the action of the acid bath on the metal is also reduced and the evolution of acid mist or fumes also great- 5 ly reduced. There is also a saving in the acid as well as a protection of the metal. The reduced amount of action of the acid on the metal and the reduction in amount of hydrogen produced correspondingly reduces the amount of hydrogen absorbed by the metal.

The employment of the condensation prodnot in the pickling or cleaning operation, ac-

cording to the present invention, involves but small additional expense and results in advantages in operation, economy of acid, protection of the metal from attack, etc., which materially improve the pickling and cleaning cleaning bath and inhibiting the chemical action of the acid on the metal without interfering with the removal of scale or oxide, and

thereby reducing the formation of hydrogen.

andthe production of acid fumes and effecting an economy in the acid consumed, by incorporating in the acid bath a small amount of a condensation product of a nitrogenous base with a ketone.

2. The method of cleaning or pickling metals which comprises subjecting the same to a non-oxidizing mineral acid pickling or cleaning bath and inhibiting the chemical action of the acid on the metal without interfering with the removal ofscale or oxide, and thereby reducing the formation of hydrogen and the production of acid fumes and effecting an economy in the acid consumed, by incorporating in the acid bath a small amount of a condensation product of acetone with a compound of the formula NH R.

3. The method of cleaning or pickling metals which comprises subjecting the same to a non-oxidizing mineral acid pickling or cleaning bath and inhibiting the chemical action of the acid on the metal without interfering with the removal of scale or oxide, and thereby reducing the formation of hydrogen and the production of acid fumes and effecting an economy in the acid consumed,

by incorporating in the acid bath a small amount of a condensation product of acetone with ammonia.

4. The method of pickling or cleaning iron or steel which comprises subjecting the same to an acid pickling bath containing sulfuric acid and inhibiting the chemical action of the acid on the metal without interfering with the removal of scale or oxide, and thereby reducing the formation of hydrogen and the production of acid fumes and effecting an economy in the acid consumed, by incorporating in the acid bath a small fraction of one percent of a condensation product of a nitrogenous base with a ketone.

5. The method of pickling or cleaning iron or steel which comprises subjecting the same to an acid pickling bath containing sulfuric acid and inhibiting the chemical action of the acid on the metal without. interfering with. the removal of scale or oxide, and thereby reducing the formation of hydrogen and the production of acid fumes and effecting an economy in the acid consumed, by incorporating in the acid bath a small fraction of one percent of a condensation product of acetone with a compound having the formula NH R.

6. The method of pickling or cleaning iron or steel which comprises subjecting the same to an acid pickling bath containing sulfuric acid and inhibiting the chemical action of the acid on the metal without interfering with the removal of scale or oxide, and thereby reducing the formation of hydrogen and the production of acid fumes and efiecting an 8 economy in the acid consumed, by incorporating in the acid bath a small fraction of one percent of a condensation product of acetone with ammonia.

7. A non-oxidizing mineral acid bath for pickling or cleaning metals which contains a small amount of a condensation product of a nitrogenous base with a ketone.

8. A non-oxidizing mineral acid bath for pickling or cleaning metals which contains a fraction of one percent of a condensation product of acetone with a nitrogeneous base.

9. A bath for pickling or cleaning iron or steel which comprises sulfuric acid and a small amount of a condensation product of duct of acetone with a nitrogenous base.

10. A bath for pickling or cleaning 11011 or steel which comprises sulfuric acid and a fraction of one percent of a condensation product of acetone with ammonia.

11. A bath for pickling or cleaning iron or steel which comprises sulfuric acid and a condensation product of a nitrogenous base with a ketone.

12. A bath for pickling or cleaning iron or steel which comprises sulfuric acid and a condensation product of acetone with ammonia.

13. A non-oxidizing mineral acid bath for pickling or cleaning metals which contains a condensation product of acetone with a nitrogenous base.

14. A non-oxidizing mineral acid bath for t pickling or cleaning metals which contains a condensation product. of acetone with ammonia.

In testimony whereof I aflix my signature.

1 GEORGE D. CHAMBERLAIN. 

